1. Field of the Invention
This invention relates to an image observation apparatus used for observing an operative site in an enlarged scale during a surgical operation. The fields of surgical operations include neurosurgery, ophthalmology and orthopedic surgery and the like.
2. Description of the Related Art
In recent years, surgical operations are often performed in a style in which an image of an operative site is displayed on an image display unit such as an LCD monitor of a display apparatus. The surgeon observes the displayed image on the display unit to carry out a desired treatment. In practice, however, many treating devices or other observation devices are concentrated near the operative site. Therefore, it is desirable that the image observation apparatus be easily installed at a position that does not interfere with those many other devices. Specifically, if the image observation apparatus is located such that the surgeon has to look up, the surgeon becomes fatigued over time. Therefore, as a first requirement, when the image observation apparatus needs to be moved, it is desirable that the image display unit of the image observation apparatus be kept at a sufficient distance from the surgeon within the same horizontal plane, i.e., at the height of the surgeon's eyes.
On the other hand, the surgeon may often need to observe the operative site directly, without using the image observation apparatus. In the course of an operation, the surgeon may need to alternate between using the monitor observation and direct-viewing of the operative site. Therefore, as a second requirement, it is desirable that the image observation apparatus be easily movable away from the operative site when the apparatus is not in use.
In a lengthy operation, moreover, many surgeons often attend the operation alternately. Therefore, as a third requirement, it is desirable that the position of the image observation apparatus be easily adjustable during the operation to accommodate the height of the current surgeon.
In addition to the first to third requirements described above, the image observation apparatus should be sized to save space in the crowded operating room where many devices are arranged around the patient. Therefore, if a supporting device of the image observation apparatus is large-sized or if an additional space is required for the position change of an image display unit, it difficult to arrange necessary devices in the operating room. This difficulty may leads to a problem of lowering efficiency of the operation.
In view of such a problem, JP-A-7-16238 and JP-A-11-318936 have proposed an image observation apparatus, in which a display device such as a monitor is movably provided in three dimensional space with a multi-articulated arm-structure having a plurality of articulations for supporting the image display device. An operator must select a plurality of appropriate arms and actuate the selected arms to locate the display device at a disable position.
JP-A-2003-233031 has proposed an image observation apparatus wherein a display device, as an image display unit, comprises an image projecting unit and a light reflecting member instead of the monitor. The image projecting unit and light reflecting member are arranged to face each other while keeping their relative positions constant through a support member having a similar multi-articulated arm structure. In this display device of JP-A-2003-233031, moreover, there is also disclosed a technique, in which the second requirement can be met by making the light reflecting unit detachable from the support member.